Extensive applications of fine particle ˜materials have been expected for biotechnology. In particular, the application of nanoparticle materials generated based on the advancement of nanotechnology to food, cosmetics, pharmaceutical products, and the like has been actively discussed. In this regard, the results of many studies have been reported.
For instance, regarding cosmetics, more obvious skin-improving effects have been required in recent years. Manufactures have been attempting to improve the functionality and usability of their own products and to differentiate their own products from competitive products by applying a variety of technologies such as nanotechnology. In general, the stratum corneum serves as a barrier for the skin. Thus, medicines are unlikely to permeate therethrough into the skin. In order to obtain sufficient skin-improving effects, it is essential to improve the skin permeability of active ingredients. In addition, it is difficult to formulate many active ingredients due to poor preservation stability or tendency to result in skin irritancy, although they are highly effective to the skin. In order to solve the above problems, a variety of fine particle materials have been under development for the improvement of transdermal absorption and preservation stability, reduction of skin irritancy, and the like. Recently, a variety of fine particle materials such as ultrafine emulsions and liposomes have been studied (e.g., Mitsuhiro Nishida, Fragrance Journal, Nov., 17 (2005)).
With the use of polymeric materials instead of emulsified products or liposomes, it can be expected that remarkable improvement in preservation stability and in in vivo particle stability will be achieved due to the structure of such material. However, in most studies, synthetic polymers obtained by, for example, emulsion polymerization are used, so that it is required to obtain safer carriers.
Further, Hiroki Fukui, Polymer, October, 798 (2006) describes the study of reservoir properties of a phospholipid polymer nanoparticle whereby an active ingredient is maintained in hair. However, it is not easy to design and synthesize such self-organized polymer. Thus, it is difficult to commercialize such polymer in terms of cost.
As an aside, hair is damaged by environmental factors such as ultraviolet irradiation and chlorine contact, chemical factors such as coloring, decoloring, permanent wave, and hair washing with the use of shampoos comprising strong surfactants, and physical factors such as the overuse of dryers at high temperatures.
Such damage results in unfavorable hair conditions such as loss of cuticles or proteins and hardened, brittle, or split hair.
Hitherto, many ingredients have been said to be effective for treatment or prevention of hair damage. Such ingredients have been used for protection of hair from ultraviolet rays or dryness, enhancement of hair volume or strength, prevention of hair loss, improvement against hair decrease, and the like. However, the above ingredients are not sufficiently effective.
Meanwhile, it is also important for a hair growth agent not only to contain an excellent hair growth component but also to have an active ingredient that can be securely delivered to action sites.
In addition, some compositions for hair contain 50% or more ethanol, and its adverse effects on the scalp are causes for concern. In the field of hair growth agents, hair growth agents generally contain 50% or more ethanol in order to dissolve hydrophobic hair growth components so that adverse effects caused by ethanol are causes for concern. JP Patent Publication (Kokai) No. 2006-176447 A suggests that scalp irritation caused by ethanol can be alleviated by a composition for hair.